No. 5.— CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY 



OF THE MUSEUM OF COMPARATIVE ZOOLOGY AT HARVARD 



COLLEGE. E. L. MARK, Director. No. 223. 



The Reactions of Amphibians to Monochromatic Lights of Equal 



Intensity. 



By Henry Laurens. 



TABLE OF CONTENTS. 



Page 



I. Introduction 2.54 



II. Methods 258 



1. Apparatus 258 



A. The light generator 2.59 



B. The combmed apparatus 259 



2. Material 263 



III. Observations 264 



1. " Reactions to single monochromatic lights 264 



A. Reactions with both the skin and the eye as recep- 



tors 264 



B. Reactions with the eye as receptor 267 



C. Reactions with the skin as receptor 269 



D. Reactions of normal toads compared with those of 



toads from which the eyes had been removed . . 272 



E. Summary 275 



2. Reactions to balanced pairs of monochromatic lights . . 277 



A. Lights of different wave-lengths 277 



a. Reactions with both the skin and the eyes as 

 receptors 277 



b. Reactions with the eyes as receptors .... 282 



c. Reactions with the skin as receptor .... 286 



B. Lights of the same wave-lengths 289 



Reactions with both the skin and the eyes as 



receptors 289 



C. Summary 290 



IV. Discussion 292 



V. Summary 299 



VI. Bibliography 301 



